The invention relates to a dosimeter for ionizing radiation comprising a gas-filled measuring chamber surrounded by a casing in which there extend a number of anode wires, which carry a fixed electrical voltage in operation, and at least one cathode element, which casing is provided with at least one entry window for the ionizing radiation.
Such dosimeters are already known from the Handbook on Synchrotron Radiation, vol. 1A, pages 323-328 by Ernst Eckhard Koch, published by North-Holland Publishing Company, Amsterdam, New York, Oxford, 1983. A drawback of said known dosimeters is that application thereof in slit radiography equipment, in which, during the production of a radiograph, it has to be possible to measure and regulate the quantity of radiation in each diaphragm section transmitted through a diaphragm slit at any instant, is not readily possible. An example of such slit radiography equipment, in which use is not made, however, of a dosimeter of the type described above, is described in Dutch patent application No. 8400845. The known dosimeters are not designed to attenuate the radiation, the intensity of which has to be measured, as little as possible and to prevent the formation of a visible X-ray shadow image of the dosimeter itself as much as possible. This latter is, however, of great importance in slit radiography equipment because the radiation transmitted through the dosimeter has to produce the required radiograph. The shape and dimensions of the known dosimeters also make them unsuitable for application in slit radiography equipment.